The lifetime of total hip replacements (THR) is often limited by adverse local tissue reactions to corrosion products generated from modular junctions. Two prominent damage modes are the imprinting of the rougher stem topography into the smoother head taper topography (imprinting) and the occurrence of column-like troughs running parallel to the taper axis (column damage). It was the purpose of this study to identify mechanisms that lead to imprinting and column damage based on a thorough analysis of retrieved implants. 776 femoral heads were studied. Heads were visually inspected for imprinting and column damage. Molds were made of each head taper and scanned with an optical coordinate measuring machine. The resulting intensity images were used to visualize damage on the entire surface. In selected cases, implant surfaces were further analyzed by means of scanning electron microscopy (SEM) and white light interferometry. The alloy microstructure was characterized for designs from different manufactures.INTRODUCTION
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